This invention relates to point attachments for foundation piles and, more particularly, to pile points ideally suited for sloping rock or batter pile applications.
As stresses permitted on steel increase and design loads become heavier, it is more essential than ever that every pile reach bearing depth in dependable condition. Various types of attachments have been developed, which are affixed to the standard forms of foundation pile, e.g. an H-beam pile, and which provide necessary protection for the pile as it is driven through the layers of earth to secure bearing on solid rock. One such attachment, known in the industry as a PRUYN POINT and marketed by Associated Pile & Fitting Corp. of Clifton, N.J., is described in U.S. Pat. No. 3,123,978. This type reinforcing point has revolutionized the industry. It has proven itself time and time again, in varying soil conditions, as a superior form of reinforcement for preventing tip damage when compared to others such as the plate and angle type, with the result that the piles drive much straighter and provide greater penetration to a dependable bearing, thus achieving adequate load carrying capacity.
Typically, the angular cut (reference member II in the aforementioned patent) is selected to accommodate the anticipated rock slope based on sub-soil tests. Of course, practically speaking, such tests cannot accurately locate and characterize all the sloping rock formations which will be encountered.
Thus, if the angular cut is less acute than the angle of the ultimate bearing surface, the particular pile point selected is unable to grab a toe hold in the rock surface with the result that the point and pile are forced off the vertical and aligned with the plane of the rock surface. Eventually, the rock surface might take an inclination towards the horizontal allowing the point to grab a toe hold, but more than likely, the slope continues at the same angle necessitating "abandonment" of the damaged pile, a redesign of the "cap" for the pile arrangement and driving of new piles fitted with points having an angular cut adequate to take the necessary bite in the surface. This quite obviously is an extremely wasteful, time consuming and consequently costly procedure.
Further, it is well known in the foundation business to drive piles at varying degrees of batter--i.e. inclined to the vertical. E.g. reaction piles in bridge foundation construction. Under these driving conditions where the rock is horizontal or slopes away from the entering pile, the problem of securing a toe hold is much more difficult than if the pile was entering along the vertical.
It is therefore, a primary object of this invention to provide a reinforcement point for a pile which gives assurance of penetrating into and gripping the bearing rock surface to thereby prevent any slippage where the rock or the pile slope sharply.
It is yet another object of this invention to provide such a pile point, which will extend the versatility of known reinforcement points, giving them wider application for varying slopes of the rock bed.